Replaceable bit rock drill



zmom

Feb. m, 193.,

c. ERICKS ON REPLACEABLE BIT ROCK DRILL Original Filed July 28, 1932 lni B Inventor BEHIBKSDN Hbt-urnqg Patented Feb. 11,1936

UNITED STATES REPLACEABLE BIT ROCK DRILL Charles Erickson, KirklandLake, Ontario, Canada Application July 28, 1932, Serial No. 625,233Renewed ctoberl5, 1935 7 Claims.

The invention relates to a replaceable bit rock drill, as described inthe present specification and illustrat in the accompanying drawingwhich forms a part of the same.

The invention consists essentially in the relative features of bit andjaws in regard to effect of the impact at the point of contact aspointed out in the claims for novelty following a description in detailof the corelated parts making up this invention.

The objects of the invention are to construct a new form of replaceablebit andshank for rock drills that will not plug when dropped into a,

muddy hole, or when used for drilling in soft ground and that willtransmit the impact from the machine to the striking faces of the shankand bit and thence to the cutting edge of the bit, rather than straightfrom the machine to the cutting edge of the bit as is usually done, thusgiving the bit which is loosely held and light, reat freedom of movementwhich results in the bit drilling a slightly larger hole than would bethe case with the usual solid construction, which consequently enablesthe bit to turn very easily and will facilitate the work of the minersand others in drilling operations by enabling them to renew their drillpoints at'the work instead of turning the cumbersome bars into theblacksmiths shop thus eliminating the necessity of the carriage of heavysteel bars and the expense of shaping them; to furnish replaceable bitsefficiently tempered and of good cutting steel which can be inserted inshanks of tougher steel'or other metal thereby increasing the value ofthe bits for the work in hand which will effect great economy in theemployment of labor and in the consump--.

: tion of material; to give prospectors a simple and light drillingoutfit that can be readily transported and materially lighten the pack;and generally to provide a drill simple to manufacture and durable forhand or machine use.

In the drawing, Figure 1 is a side elevational Figure 4 is a fragmentaryelevational view of the end of a shank.

Figure is a cross sectional view of the shank taken on the lines 5-5 inFigure 4.

Figure 6 is an enlarged perspective view of one of the replaceable bits.

Like numerals of reference indicate corresponding parts in the variousfigures.

Referring to the drawing, the shank is indicated by the numeral l0 andis formed either of the drill steel itself if it is of large enoughdiameter or with the upset stock ll of a large enough diameter toprovide sufiicient strength across the base wall l2 from which projectthe jaws l3 and I4, the jaws l3 and i4 being chamfered on the outside atE5 and i6 and radiused on the inside end to the narrow end faces H andi8 adapted to be over-hung by a bit. The walls It and of the jawsconverge from the fillets 2i and 22 in the corners to constitute adovetail slot for receiving a correspondingly shaped portion of the bitand in each case form a radius running into from eitherside the innerimpact wall 23 which bevels into the water passage 2Q through the drillsteel and thereby insuring a free flow of water to the cutting edges ofthe replaceable bit 25.

The replaceable bit 251s of spearhead shape in cross section and thusover-hangs the end faces l1 and i8 and the striking surface 2% is softerthan the impact wall 23 of the base wall l2 thereby taking all the wearand upsetting due to the bit being softer than the shank and in that waythe shank will outlast many bits.

The bit 25 has the radius 21 larger than the corresponding radius of theshank and is formed of the converging walls 28 and 29 which form adovetail portion on the bit adapted to be received into the dovetailslot in the shank which are adapted to nearly correspond with theconverged walls l9 and 20 of the jaws l3 and Hi, the difference betweenthe two being that the walls 28 and 29 converge faster than the others,thereby ensuring the bit being held by the base .of the jaws l3 and ll,rather than up at the end of them, the converging walls 28 and 29 of thebit merging into the shoulder portions 30 and. 3| which merge in thebevelled walls 32 and 33 terminating in the cutting edge 34.

It will therefore be noted that the differences in radii of thereplaceable bit and the jaws of the I shank materially lessen thesurface contact and thereby provide clearances where the metal of thebit, due to the impacts on the striking surface, will tend to flowrather than expand sideways against the jaws, thus causing strain,binding and breakage.

The length of the striking surface of the bit is smaller than thediameter of the upset stock which is for the purpose of enabling theexpansion of the bit lengthwise when it is upset at the base so that theincreased length will not protrude past the side and form a. shoulderwhich would make it diflicult to extract the used bit.

In the operation of the invention, a hole is first drilled in the rockwith an ordinary starter for about three inches, the replaceable bit isthen simply slid in between the jaws of the upset stock and is preventedfrom slipping out endways by the converged walls of the jaws andsideways by the fingers until the steel is in the hole, when the holeprevents the bit from coming out from between the jaws and the steel isthen ready for drilling purposes.

The dovetail portion of the bit 25 is permitted a limited longitudinalmovement in the dovetail slot in the shank as will be seen uponreference to Figs. 2 and 2A, and thus in operation the bit gives atapping action due to the loose connection which is particularlyefiective in drilling the hole.

When the bit has been worn out through use it is simply slid out ofposition and scrapped and a new bit inserted. I

This bit will drill faster, further and last longer than the standardcross bit.

What I claim is:

1. A replaceable bit rock drill comprising a holder for a replaceablebit having traverse jaws converging towards their extremities from astriking surface removed from said jaws by grooves, said strikingsurface being pierced by the central bore of. the holder,.and a bithaving a cutting edge supported by a shank flaring outwardly to the baseand vslidably fitting between said jaws and said striking surface, andthe shank of said bit continuing beyond the extremity of the jaws of theholder without increasing in size and then flaring outwardly to supportsaid cutting edge and without contact with the extremity of said jaws.

2. In a replaceable bit rock drill, a holder and bit together forming aloose dovetail joint, the

bit having free lateral movement for shaping the hole and a. limitedlongitudinal movement, said longitudinal movement contributing to a.direct impact by the striking base of the tenon cut, at each stroke ofsaid holder distinct from the origin of the stroke and to a swagingaction on the bit, said striking base extending through fillets into theconverging side walls of the cut at either side of the cooling fluidinlet.

3. In a replaceable bit rock drill, a shank having a longitudinaldovetail slot at its end, a bit having a cutting edge and a longitudinaldovetailportion removably received into the dovetail slot in the shankend such that the dovetail portion on the bit is permitted a limitedlongitudinal movement in the dovetail slot in the shank end.

4. A construction as claimed in claim 3 wherein the dovetail slot in theshank extends to its wall and the dovetail portion of the bit ispermitted free lateral movement in such slot.

5. The combination with a shank and a detachable bit therefor, of aloose connection therebetween such that the bit is permitted a limitedlongitudinal movement and in addition free lateral movement in theshank. V

6. The combination with a shank having a longitudinal dovetail slot inthe end thereof defined by converging side walls and a transverse bitimpact surface, of a detachable bit having a cutting edge and'alongitudinal dovetail portion inserted into the dovetail slot in theshank and defined by diverging walls and a transverse upper surfaceadapted to engage the said impact surface in the slot of the shank, saiddovetail portion of the bit being permitted a limited longitudinalmovement in the dovetail slot of the shank.

7. The construction claimed in claim 6 wherein the dovetail portion ofthe bit is permitted free lateral movement in the dovetail slot in theshank.

CHARLES ERICKSON.

